Oscilloscope Shopping on a $2000.00 Budget

i have seen that in about a dozen scopes. it is usually a resistor opening up in the focus and brightness pot string Average cost to repair is a buck.

I had a Leader LB 505 that was so old, it was built with US made transistors. The manual showed Jap 2S parts, but it was built with @N parts. I bought it new just after I got out of the service. It was stolen a few years later. :(

They might of did you a favor! :)

Try the Hewlett-Packard 130C. It was the last decent oscilloscope they ever built.

Ok... I'm now reading on the

Instek GDS2204 DSO 200Mhz 4ch at ~$1600.00 EZ Digital DS1250 DSO 250Mhz 2ch at ~$2000.00 Rigol DS5202CA DSO 200Mhz 2ch at ~$2000.00 Tektronics TDS2022B DSO 200Mhz 2ch at ~$1800.00 PICO Tech. PC based oscilloscope 3206 200Mhz 2ch at ~1500.00

Memory depths and sample rates vary.. Should be all colour displays. Prices from 1st find off Google

At current... for 200Mhz BW... price ~= BW*10 I sense this is the current knee region. Any more BW and the price starts to sharply rise.

I suspect in this BW/price region...whoever offers the most memory depth may be the better deal.

D from BC

The cheapies, with low sample rates, switch to equivalent-time mode at high sweep speeds, and often do even that badly. My cheap TDS2012 samples at 1 Gs, and our 500 MHz thing samples at 4 GHz. They do alias, but you get used to that pretty fast. The aliasing trades off against the fact that a single shot waveform is perfectly visible at any sweep speed, and infinite persistance can catch all sorts of rare, nasty events.

I hated digital scopes at first, because they were too hard to drive. We demoed one Agilent that nobody could get to work, the menus were so obscure. But now they have all the good old knobs and buttons that God intended a scope to have.

Our TPS2024 is 4 channels, 200 MHz, 2 gs/s, fully isolated - even the trigger input - and comes standard with battery power. Fabulous for working on power amps, what with opamps and fets riding 200 volts off ground. Cool black BNCs on the front panel.

Our EMI environment is so extreme, it just adds spice to the mix.

John

Heyy..isn't that from the 60's??

Oh nooo... If I buy a DSO, I might need to get an analog scope too so that I can confirm strange waveform results on the digital scope. :( Maybe call it "Digital Scope Training with help from an Analog Scope". :) D from BC

D from BC hath wroth:

Too long to wait. Buy the scope early and depreciated it on this years taxes.

I have 15 assorted scopes (10 of which actually work) between the house, shop, and office. I think I'm down to about 6 scope probes. Despite all these scopes, the ones I use most are various PC sound card based software oscilloscopes, audio spectrum analyzers, and tone generators. Yeah, I know the frequency range is limited to audio and it won't do DC, but otherwise, the software scopes have the all the computerish benifits of a real DSO. My favorite for the week is:

Rigol design and manufacture the low end Agilent digital scopes, exactly the same scope but with Agilent branded on it. That should give you a lot of confidence in the construction, performance, and firmware. They roll their own ADC front end too, something that the other no-namers can't and don't do. So if you are looking at the low end Agilents, consider the Rigol, you might be able to pick up the exact same scope for a bit less.

Dave.

Well, mine's 1Gs/sec as well but for many higher frequency switchers that ain't fast enough. Once it goes into equivalent time that's when I pull the power knob on the 7000 series mainframe and that marvelous blue light emerges from its screen.

But that thing plays in another league in terms of cost.

The issue I had with the TDS was conducted noise spilling out via the probe lines. Pathetic. I am pretty sure that wouldn't have happened were the old guys still there. I think they even had some kind of recall because they also botched the PE grounding on some models. I wonder why that wasn't caught in a design review or during tests. They are supposed to be the Mercedes-Benz in oscilloscopes.

One of my customers has a new 8 GHz (40 gs/s or something absurd like that) Agilent scope that cost close to $100K. He says it's hard to get it to trigger!

John

If you buy the Hameg you'll have both worlds. But it'll be above $2K. I'd seriously ask myself how much BW I really need. For uC you can live with 100MHz IMHO. That might leave enough dough for a cheap (or used) analog scope for SMPS projects. Picture this: You'll get to open two presents instead of one!

If you plan to do uC work with a DSO that does not feature a built-in little logic analyzer then two channels ain't enough. For example, lately I had to debug a SPI bus together with a software guy. Requires three channels and for bidirectional operation (which is the usual method) four channels. But you don't really need 200MHz for such jobs.

Yep, pretty much.

Depends on what you want to do. For switchers you don't need lots of memory. For lengthy SPI, I2C oder other serial comms you do. Remember that most DSO lack delayed trigger so often you are pre-filling memory with junk until it gets to the point you want to look at. With the paltry 2500 samples of a TDS that's often next to impossible. The other end of the spectrum would be the Hameg which can store humongous amounts.

As to PC scopes keep in mind that SMPS work entails the occasional "kablouiue" situation. A scope is pretty sturdy. But is the PC? Or will it release a puff of smoke when the USB ground gets hit?

I haven't used an analog scope for several years. I'd say they still have their place for low-level work, though. I agree with most of John Larkin's comments in this thread. It's really pretty easy to check for aliasing. D from BC, I'd say that you should save some of your budget for a current probe rather than an analog DSO. Paul Mathews

Fet probes are the real killer. The difference is astonishing.

I don't know why they're so expensive.

John

It's easy to check for aliasing if you roughly know what to expect. Many times that's not the case. Also, the fact that DSO designers thought it smart to remove greatly needed features such as delay trigger and even holdoff (!) doesn't exactly make it easy to obtain a proper scan. Sometimes I wonder how many of the DSO designers have actually worked in hardcore circuit design these days.

Yeah... I should pick up on the DSO quirks. "My god.. It's full of stairs!" (ok..a little spoof on the movie 2001)

I'm thinking of buying a new DSO to test drive for smps development.. If it sucks...then it gets used for my uC projects and then I buy an Ebay analog scope for smps work.

D from BC

Are the floating inputs in the probes or in the scope? I am working on a SMPS with uC control and don't have a scope yet, figure I better get one so I am in the market too!

cheers, Jamie

In the scope itself. I'm not sure, but I think they use GHz-range FM to couple the signal from the floating input stage to ground-referenced. It comes with special safety-rated probes (no exposed metal) but any probes, or no probes, work fine. TPS2000 series, starts around $2500, not bad if you consider what isolation probes cost.

John